1. Field of the Invention
The present invention relates to a procedure for disinfecting and cleaning contact lenses, comprising introducing the lenses into a container containing therein an aqueous hydrogen peroxide solution and a destabilizer component therefor in a totally uncoated tablet, prepared in such a way that enables this component to cause controlled peroxide destabilization from the first instance and to maximize its oxidizing action in order to achieve a more efficient lens disinfection and cleaning. As a final result of the process, there is a hydrogen peroxide degradation that results in levels that allow the transformed solution to be compatible with the eye and to maintain the contact lens cleanliness parameters.
2. The Prior Art
Contact lenses in continuous use build up a series of fatty, proteinic, or other kinds of, deposits which act as substrates, allowing environmental microorganisms which are dangerous to the lens itself, and which may even be dangerous to the eye, to be deposited on the substrate. Because of this, several means for disinfecting the lenses have been devised. The most often used procedure is based upon using hydrogen peroxide which possesses a high disinfecting power without damaging the lens morphology, and which leaves no noxious traces once it has been removed.
Using hydrogen peroxide or oxygenated water, however, poses a problem unless it is eliminated once it has concluded its cleaning function, since any trace of this substance on a lens may cause serious irritations to the eye. Thus, the usual procedure consists in first disinfecting the lens with the hydrogen peroxide contained in a suitable container. Then, once the lens has been disinfected, to neutralize the hydrogen peroxide in a second step by any known means, such as chemical compositions, or rinsing with saline water, in such a way that the hydrogen peroxide concentration in the solution is reduced down to a level not damaging to the eye.
It is evident that this two-phase method has the drawback of being slow; and it even implies running the risk on the user's part that the user must adequately oversee completing the process.
In order to overcome this inconvenience, other methods have been further proposed. For example, there is performing the disinfection step and the neutralization step in one method procedure only. That is by introducing the lens into a container simultaneously holding hydrogen peroxide and all the other ingredients required to neutralize it. This will form at the same time an idoneous lens maintenance solution. Also used are methods to delay the neutralizing action by placing layers on the lens which are appropriate substances which will eventually dissolve after some time delay, or other galenic preparation forms as described in the Ciba-Geigy AG patent 86/01791. Some of these prior art forms are very difficult to prepare.
This prior art method, contrary to the present invention, does not seek to increase the hydrogen peroxide oxidative effect, but that by delaying for some previously set time the starting of the neutralizer action, allows lenses to get in contact with the hydrogen peroxide at its maximum although stabilized concentration. It is after the above-mentioned previously set time when the total neutralizer is released in a fast manner, thus destroying hydrogen peroxide in order that the lens will cause no harm to the eye.
Thus, the only apparent reason for including a neutralizer herein is to destroy the excess hydrogen peroxide.
other methods for the one-step procedure to neutralize hydrogen peroxide are to employ heavy metals as catalysts, such as platinum, which performs a slow neutralization, whereby the catalytic activity is reduced as the peroxide concentration is reduced. This prior art procedure is described in the Gaglia U.S. Pat. No. 3,912,451 of Oct. 14, 1975.
This method clearly differs from the present invention which achieves improved results. According to this prior art patent, contact lenses are submerged in normally stabilized hydrogen peroxide in order to have them disinfected through its standard action.
Simultaneously, or some time thereafter, a support holding a metal-type catalyst is submerged into the solution in order to start destroying the hydrogen peroxide by releasing oxygen, thus obtaining peroxide concentrations in the solution which are unable to cause eye discomfort once the contact lens has been inserted.
There is no hydrogen peroxide activation in this prior art system. On the contrary, oxygen is only released at the metal catalyst surface, forming no complex at all, and this generated oxidizing is recombined to form an oxygen molecule whose oxidative power is very low. Therefore, the hydrogen peroxide solution in the prior art is not being selectively activated, whereas in the present invention, it is selectively activated. In the prior art method, it is being deactivated. It is apparent that no other result is sought in the prior art other than eliminating hydrogen peroxide from the contact lens after disinfecting it, and that this elimination is obtained by means of a metal catalyst.
In the prior art, other single-step, single-phase methods exist which, by using physical hindrances for releasing the neutralizer, would delay the hydrogen peroxide degradation. Up to this time it has always been thought that stabilizing the peroxide concentration would always be enough during the time interval required for the peroxide to perform its disinfecting action.